Object not rendering correctly from a distance
You probably have faces that are very close together (or on top of each other).
Check your mesh for mistakes (e.g. select all in edit mode, then press W -> remove doubles).

Another thing to check is the scale of your model. If it is excessively large or small, this can cause numerical precision problems.
In such a case, scale your model, then apply the scale with Ctrl+A -> Scale.

If the problem still persists, try to adjust the start and end clipping in the camera settings. The end clipping should be just behind the object (e.g. if the object is 10 Blender units away, you could set the end clipping value to 15 or so).
Note that this tip only applies to OpenGL and Blender Internal renders, not Cycles or other engines that don't use a Z-Buffer to calculate occlusion.